Initiator



' Patented July 16, 1935 PATENT OFFICE INITIATOR Henry K. Babbitt, Wilmington, Del., and Harold A. Lewis, Woodbury, N. 5., assignors to E. I. du

Pont de Nemours & Company, Wilmington,

Del., a corporation of Delaware Application April 24, 1931, Serial No. 532,520

' 25 Claims.

Blasting caps as heretofore manufactured have usually comprised a shell of gilding metal (copper-zinc), or aluminum, or its alloys. By the term blasting caps as used herein we mean to include either a fuse or ordinary cap, anelectric blasting cap, andfor a delay electric blasting cap. Descriptions. of each type follow hereinafter. Blasting caps having mercury fulminate as the main charge or as a priming agent have usually been constructed of gliding metal, because of the compatibility of mercury fulminate with such copper alloys. Caps containing lead azide have usually been made of aluminum or its alloys, since this compound in combination with copper or copper alloys forms supersensitive copper azide, particularly in the presence of moisture and carbon dioxide, thus making such combinations hazardous and prohibitive. Furthermore, it has been found'that aluminum-shell, lead-azide primed caps give off an excessive flash upon detonation, probably because of the combustion of the aluminum shell. This flash is frequently sufiicient in intensity to ignite inflammable gases, such as are presentin gaseous coal mines, thus making this type of shell also hazardous and prohibitive.

Detonators for high explosive shells and priming cups for small arms ammunition have also commonly been made of gilding metal, of brass,

or of copper-nickel alloys. Besides excessive cost ofsuch shells and other parts made of these metals, they have had other inherent disadvan tages.

There are other disadvantages in both aluminum and copper-blasting caps, aside from cost and non-uniformity of form and composition,

in that when either is used for blasting in the mining of salt, the flne metal particles that result, are generally objectionable in the salt and render the salt unsatisfactory for many purposes; For example, when such salt is used in tanning processes, a discoloration of the hides invariably results. Furthermore, when these types of blasting caps are used in connection with the blasting of coal, any unexploded caps later present a serious hazard in the subsequent use of the coal. In either case, neither the particles nor the unexploded caps can be conveniently removed from the mined material by the most suitable means, namely, the magnet, because of the non-magnetic properties of these metals.

Other metals have been suggested for use in the manufacture of blasting caps but have not found application because of various disadvantages.

An object of our invention is to provide an initiator that is universally suitable for all types of firing and blasting operations. A further object of our invention is to provide an initiator, the metallic material of which is compatible with both mercury fulminate and lead azide. Another object of ourinvention is to provide an initiator which is constructed of less expensive materials than those heretofore known and used. A still further object of our invention is to provide an initiator, and particularly a blasting cap, that is magnetic. Other objects will be apparent as the description proceeds.

These objects are accomplished by the following invention in which we have found that rustproof or so-called stainless steel, or stainless iron, when used in combination with mercury fulminate and lead azide, is compatible therewith, yields a product that is non-corrosive, does not give off an objectionable flash when exploded, and has magnetic properties, besides many other advantages.

-By the terms rustless or stainless steels, we mean to include the common alloys of steel known in the trade as such. These comprise steels containing chromium, in amounts for example of 10 to 20 per cent, and those containing nickel and cromium in proportion, for example, of 15 to 20 per cent of chromium and 5 to 15 per cent of nickel. By the term stainless iron" we mean similar alloys to the foregoing except that the steel is low in carbon, having a carbon content of from .05 to .25 per cent. While the foregoing proportions may be used for our purpose,

we preferably use in the case of chromium alloys those containing proportions of from 15 to 18 per cent chromium alone, and thosecontaining chromium and nickel of from 5 to 15 per cent nickel. While the chromium-nickel alloy is less nitrocellulose, resins, etc., and coatings or platings of various suitable metals are satisfactory.

By way of further description and illustration of our invention, we have shown in the accompanying drawing, in sectional views three embodiments thereof applied specifically to blasting caps, in which Figure; 1, 2 and 3 represent respectively an ordinary or fuse type blasting cap, an electric blasting cap, and a delay type electric blasting cap. Figure 4 represents a detonator for a high explosive shell, and Figure 5 priming cups suitable for small arms ammunition.

In each of Figures 1, 2 and 3, A represents a stainless steel shell which may be a plain shell or one coated or plated as hereinbefore described. B represents a charge of a secondary detonating material, for example, tetryl, while C represents a charge of a primary detonating compound, for example, of lead azide. i

In Figure 2, E, F, G, and H, represent the usual elements of an electric blasting cap in which E is adapted to be fired by the bridge wire H car- 'ried by the firing wire G.

Figure 3 represents an electric blasting cap of the delay type in which the delay element K is substituted for the loose charge E in Figure 2; When fired the burning gases from the delay element may escape through the opening M and may be carried through the outer sleeve N. Elements F, I, J, and L, in Figures .2 and 3 represent a water-proofing and sealing composition. Figures 4 and 4A represent respectively a cross section and a plan view of a detonator for a high explosive shell while Figures 5 and 5A represent conventional forms andSB a View in prospective of priming cups for smalls arms ammunition of conventional design.

Whereas we have described our invention as applicable particularly to blasting caps, it will be apparent that it may equally well be applied to primers for ammunition and to detonators for high explosive shells and drop bombs.

Therefore, by the term initiators", used herein, we mean to include-blasting caps for use with commercial explosives such as dynamite, detonators for high explosive shells, depth bombs, hand grenades, and the like, and primers for small arms ammunition.

' It is to be understood that the foregoing examples are illustrative only and that other embodiments exist and may be practiced within the scope of our invention. For example, stainless steel shells may be used in combination with other explosive charges suchasthe series of so-' called straight-fulminate detonators. It is to be further understood that we do not intend to be limited in our invention except as indicated casing the charge.

l. A priming cup comprising in combination an explosive charge and a stainless steel shell encasing the charge.

5. An initiator comprising in combination a charge of a secondary detonating compound, a charge of a primary detonating compound, and a stainless steel shell encasing the compounds.

6. A blasting cap comprising in combination charge of a secondary detonating compound, charge of a primary detonating compound, and stainless steel shell encasing the compounds.

7. A detonator comprising in combination charge of a secondary detonating compound, charge of a primary detonating compound and new new stainless steel shell encasing the compounds.

8. A priming cup comprising in combination a charge of a secondary detonating compound, charge of a primary detonating compound and stainless steel shell encasing the compounds.

9. An initiator comprising in combination a charge of a secondary detonating compound, a charge of lead azide and a stainless steel shell encasing the compounds.

10. A blasting cap comprising in combination a charge of a secondary detonating compound, a charge of lead azide, and a stainless steel shell encasing the compounds.

11. A detonator comprising in combination a charge of a secondary detonating compound, a charge of lead azide and a stainless steel shell encasing the compounds.

12. A priming cup comprising in combination a charge of a secondary detonating compound, a charge of lead azide and a stainless steel shell en casing the compounds.

13. An initiator comprising in combination a charge of tetryl, a charge of lead azide, and a stainless steel shell encasing the charges.

14. A blasting cap comprising in combination a charge of tetryl, a charge of lead azide, and a stainless steel shell encasing the charges.

15. A detonator comprising in. combination a charge of tetryl, a charge of lead azide, and a stainless steel shell encasing the charges.

16,; A priming cup comprising in combination a charge of tetryl, a charge of lead azide, and a stainless steel shell encasing the charges. l7. An-initiator comprising in combination an explosive'charge and an annealed, stainless steel shell encasing the charge.

18. A blasting cap comprising in combination an explosive charge and an annealed, stainless steel shell encasing the charge.

19. A detonator comprising in combination an explosive charge and an annealed, stainless steel shell encasing the charge.

20. A priming cup comprising in combination an explosive charge and an annealed, stainless steel shell encasing the charge.

.21.- An initiator comprising in combination an explosive-charge and a coated, stainless, steel shell encasing the charge.

22. A blasting cap comprising in combination an explosive charge and a coated, stainless steel shell encasingthe charge.

23. A detonator comprising in combination an explosive charge and a coated, stainless steel shell encasing the charge.

24. A priming cup comprising in combination an explosive charge and a coated, stainless steel shell encasing the charge.

25. An initiator comprising in combination a charge ofv lead azide, and a stainless steel shell encasing the charge. I

HENRY K. BABBITT. HAROLD A. LEWIS. 

